I also remember wanting to find MORE after I read!! Fortunately there was plenty of fanfiction and fanworks to get sucked into. I remember staying up until 6 in the morning reading fanfiction on the computer on school nights because I was just so eager to have MORE content. I think it's definitely because throughout the series, the characters became people I loved and I became so invested in them. I especially found it really easy to get sucked into fanworks concerning the characters we didn't know as well because I just wanted to know more about their lives and that wasn't always something that was provided for us.

I could read about the marauders for DAYS (months? years? lifetimes?) on end